Today's consumer electronics market frequently demands complex functions requiring very intricate circuitry. Scaling to smaller and smaller fundamental building blocks, e.g. transistors, has enabled the incorporation of even more intricate circuitry on a single die with each progressive generation. Semiconductor packages are used for protecting an integrated circuit (IC) chip or die, and also to provide the die with an electrical interface to external circuitry. With the increasing demand for smaller electronic devices, semiconductor packages are designed to be even more compact and must support larger circuit density. For example, some semiconductor packages now use a coreless substrate, which does not include the thick resin core layer commonly found in conventional substrates. Furthermore, the demand for higher performance devices results in a need for an improved semiconductor package that enables a thin packaging profile and low overall warpage compatible with subsequent assembly processing.
On the other hand, although scaling is typically viewed as a reduction in size, the addition of functionality in a given space is also considered. However, structural issues may arise when attempting to package semiconductor die with additional functionality also housed in the package. For example, the addition of packaged inductors may add functionality, but ever decreasing space availability in a semiconductor package may provide obstacles to adding such functionality.
On-die voltage regulation can be used to locally change the voltage, e.g., within core voltage changes, for active power management. Additionally, On-die voltage regulation can also be designed to automatically maintain a constant voltage level for an associated semiconductor die. In another application, on-die voltage regulation can also be used to throttle voltages in real time if active power management required. A voltage regulator may be a simple “feed-forward” design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
Electronic components, such as inductors, may be implemented on substrates such as an integrated circuit die or a printed circuit board (PCB). Such implementations involve placing patterns of material (e.g., a conductive material) on one or more substrate layers. This placement may be through lithographic techniques. Inductors used for RF applications are typically air-core spiral inductors or, in some cases, ferrite magnetic inductors. Various drawbacks are associated with these inductors. For instance, air-core spiral inductors typically require a substantial amount of space (area) on a substrate (e.g., an IC die). Moreover, such inductors typically, but not necessarily, couple to a high-resistivity substrate. In other cases, a magnetic layer underneath the stripline effectively shields the substrate at the operating frequency of an associated VR.
Thus, significant improvements are still needed in the area of inductor fabrication for voltage regulation.